The recording strategy is optimized by determining a pulse response so as to minimize the difference between the reproduced waveform obtained by recording and reproducing the recording pulse signal wherein the record data is superposed with a high-frequency pulse and the waveform calculated by convolution of the record data and pulse responses. In this process, a single recording pulse waveform is recorded on a single track of the optical recording medium for three or more times, and sampled values zp,1, . . . , zp+3,1, . . . , . . . , zp,2, . . . , zp+3,2, . . . , zp,3, . . . , zp+3,3, . . . , of the reproduced waveforms reproduced therefrom are averaged in the order of the sampling to be used as the data for the reproducing waveform. Here, the first suffix for z represents the order of the sampling, whereas the second suffix represents the number of iterated times. The use of the averaged data can remove the influence by the random noise on the reproduced waveform.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for adjusting a recording condition of optical information, comprising the steps of: irradiating an optical recording medium with laser light having a recording pulse waveform generated based on a recording signal, which is in synchrony with clock cycles, to form a record mark group on said optical recording medium; reading said record mark group to obtain a reproduced waveform, and adjusting the recording condition by sampling said reproduced waveform at a period shorter than a clock period to evaluate a linearity of said reproduced waveform, wherein said adjusting step linearly interpolates sampled values of said sampled reproduced waveform at a timing of R 1 or R 2 assuming a maximum, to extract times-series data of said reproduced waveform for respective clock cycles, given R 1 and R 2 being expressed by the following formula: R1 = ( n + 1 ) × ∑ i h i 2 ∑ k ( y k - ∑ i a k - 1 × h i ) 2 and R2 = ∑ k y k 2 ∑ k ( y k - ∑ i a k - 1 × h i ) 2 (i being an integer satisfying 0≦i≦m) respectively, wherein {a 0 , a 1 , . . . , a k , . . . , a n−1 , a n } represent said times-series data for respective said clock cycles of the clock for recording said optical recording medium, {y 0 , y 1 , . . . , y k , . . . , y n−1 , y n } represent time-series data of said reproducing waveform for respective said clock cycles (n being an integer not smaller than zero, and k being an integer satisfying 0≦k≦n), and {h 0 , h 1 , . . . , h m } represent pulse responses of a recording/reproducing system corresponding to a specific recording/reproducing condition (m being an integer satisfying 0≦m≦n).
2. The method for adjusting the recording condition of optical information according to claim 1 , wherein an index of said linearity is obtained by the following formula: ɛ = ∑ k ( y k - ∑ i a k - i × h i ) 2 (i being an integer satisfying 0≦i≦m), wherein {a 0 , a 1 , . . . , a k , . . . , a n−1 , a n } represent said times-series data for respective said clock cycles of the clock for recording said optical recording medium, {y 0 , y 1 , . . . , y k , . . . , y n−1 , y n } represent time-series data of said reproducing waveform for respective said clock cycles (n being an integer not smaller than zero, and k being an integer satisfying 0≦k≦n), and {h 0 , h 1 , . . . , h m } represent pulse responses of a recording/reproducing system corresponding to a specific recording/reproducing condition (m being an integer satisfying 15≦m≦n).
3. A method for adjusting a recording condition of optical information, comprising the steps of: irradiating an optical recording medium with laser light having a recording pulse waveform generated based on a recording signal, which is in synchrony with clock cycles, to form a record mark group on said optical recording medium; reading said record mark group to obtain a reproduced waveform, and adjusting a recording condition by evaluating a linearity of said reproduced waveform, characterized in that: said adjusting step is such that an index of the linearity is obtained by the following formula: R1 = ( n + 1 ) × ∑ i h i 2 ∑ k ( y k - ∑ i a k - 1 × h i ) 2 (i being an integer satisfying 0≦i≦m), wherein {a 0 , a 1 , . . . , a k , . . . , a n−1 , a n } represent said times-series data for respective said clock cycles of the clock for recording said optical recording medium, [y 0 , y 1 , . . ., y k , . . . , y n−1 , y n ] represent time-series data of said reproducing waveform for respective said clock cycles (n being an integer not smaller than zero, and k being an integer satisfying 0≦k≦n) and {h 0 , h 1 , . . . , h m } represent pulse responses of a recording/reproducing system corresponding to a specific recording/reproducing condition (m being an integer satisfying 15≦m≦n).
4. A method for adjusting a recording condition of optical information, comprising the steps of: irradiating an optical recording medium with laser light having a recording pulse waveform generated based on a recording signal, which is in synchrony with clock cycles, to form a record mark group on said optical recording medium; reading said record mark group to obtain a reproduced waveform, and adjusting the recording condition by evaluating a linearity of said reproduced waveform, characterized in that: said adjusting step is such that an index of the linearity is obtained by the following formula: R2 = ∑ k y k 2 ∑ k ( y k - ∑ i a k - 1 × h i ) 2 (i being an integer satisfying 0≦i≦m), wherein {a 0 , a 1 , . . . , a k , . . . , a n−1 , a n } represent said times-series data for respective said clock cycles of the clock for recording on said optical recording medium, {y 0 , y 1 , . . . , y k , . . . , y n−1 , y n } represent time-series data of said reproducing waveform for respective said clock cycles (n being an integer not smaller than zero), and k being an integer satisfying 0≦k≦n), and {h 0 , h 1 , . . . , h m } represent pulse responses of a recording/reproducing system corresponding to a specific recording/reproducing condition (m being an integer satisfying 15≦m≦n).
5. The method for adjusting the recording condition of optical information according to claim 3 or 4 , wherein said adjusting step includes the steps of sampling said reproduced waveform at a period shorter than a clock period, and extracting time-series data of said reproduced waveform for respective said clock cycles by linearly interpolating sampled values of said sampled reproduced waveform at a timing of said R 1 or R 2 assuming a maximum, given R 1 and R 2 being expressed by the following formula: R1 = ( n + 1 ) × ∑ i h i 2 ∑ k ( y k - ∑ i a k - 1 × h i ) 2 and R2 = ∑ k y k 2 ∑ k ( y k - ∑ i a k - 1 × h i ) 2 (i being an integer satisfying 0≦i≦m) respectively, wherein {a 0 , a 1 , . . . , a k , . . . , a n−1 , a n } represent said times-series data for respective said clock cycles of the clock for recording said optical recording medium, {y 0 , y 1 , . . . , y k , . . . , y n−1 , y n } represent time-series data of said reproducing waveform for respective said clock cycles (n being an integer not smaller than zero, and k being an integer satisfying 0≦k≦n), and {h 0 , h 1 , . . . , h m } represent pulse responses of a recording/reproducing system corresponding to a specific recording/reproducing condition (m being an integer satisfying 0≦m≦n).
6. The method for adjusting the recording condition of optical information according to any one of claims 1 , 2 , 3 , and 4 , wherein said optical recording medium is a phase-change optical recording medium, and wherein, upon forming said record mark group on said phase-change optical recording medium by irradiating said phase-change optical recording medium with the laser light, an overwrite operation is conducted twice before obtaining said reproduced waveform.
7. The method for adjusting the recording condition of optical information according to any one of claims 1 , 2 , 3 , and 4 , wherein three or more of said record mark groups are recorded using recording pulse waveforms having the same form, said record mark groups are reproduced to sample three or more reproduced waveforms, and samples values of said sampled reproduced waveforms are averaged.
8. The method for adjusting the recording condition of optical information according to any one of claims 1 , 2 , 3 , and 4 , wherein said record mark group is recorded by using a single recording pulse having a specific waveform, and said record mark group is reproduced for three or more times to sample three or more reproduced waveforms, and sampled values of said sampled reproduced waveforms are averaged.
9. The method for adjusting the recording condition of optical information according to claim 7 , wherein said three or more record mark groups are formed on a single track of said optical recording medium.
10. The method for adjusting the recording condition of optical information according to claim 3 , wherein said R 1 is adjusted so as to satisfy 10×log R 1 >20-20(l/w) dB, given “w” being a beam diameter of the laser beam used for recording/reproducing information, given “l” being a shortest mark length to be recorded on the optical-information recording medium.
11. The method for adjusting the recording condition of optical information according to claim 4 , wherein said R 2 is adjusted so as to satisfy 10×log R 2 >21-20(l/w) dB, given “w” being a beam diameter of the laser beam used for recording/reproducing information, given “l” being a shortest mark length to be recorded on the optical-information recording medium.
12. The method for adjusting the recording condition of optical information according to claim 2 , 3 , 4 , 10 or 11 , wherein said h i has a value determined using a least-squares method, and has a non-zero width larger than 15T, given T being a reference clock of data.
13. The method for adjusting the recording condition of optical information according to any one of claims 1 , 2 , 3 , 4 , 10 , and 11 , wherein, when the data recorded on said optical information recording medium are expressed by “1” or “0”, a reference data is added before said recording signal as a reference timing for sampling said reproduced waveform, said reference data having a duration of data “1” or data “0” different from the width of said recording signal.
14. A recording/reproducing apparatus for optical information, comprising: an optical head irradiating an optical recording medium with laser light to receive reflected light therefrom; a laser drive for changing an optical intensity of an laser output thereof; and a control section having the functions of: converting a recording signal, which is in synchrony with clock cycles, into a recording pulse waveform to transmit the same to said laser drive; sampling a reproduced waveform, reproduced from record marks on said optical recording medium, at a period shorter than a clock period; interpolating the sampled values; evaluating a difference between a waveform obtained by convolution of pulse responses determined from said reproduced waveform and said recording signal and a waveform obtained by sampling said reproduced waveform and interpolating sampled values thereof at a timing of R 1 or R 2 assuming a maximum, to adjust a width or power of said recording pulse waveform, given R 1 and R 2 being expressed by the following formula: R1 = ( n + 1 ) × ∑ i h i 2 ∑ k ( y k - ∑ i a k - 1 × h i ) 2 and R2 = ∑ k y k 2 ∑ k ( y k - ∑ i a k - 1 × h i ) 2 (i being an integer satisfying 0≦i≦m) respectively, wherein {a 0 , a 1 , . . . , a k , . . . , a n−1 , a n } represent said times-series data for respective said clock cycles of the clock for recording said optical recording medium, {y 0 , y 1 , . . . , y k , y n−1 , y n } represent time-series data of said reproducing waveform for respective said clock cycles (n being an integer not smaller than zero, and k being an integer satisfying 0≦k≦n), and {h 0 , h 1 , . . . , h m } represent pulse responses of a recording/reproducing system corresponding to a specific recording/reproducing condition (m being an integer satisfying 0≦m≦n).
15. The recording/reproducing apparatus according to claim 14 , wherein said evaluating is such that an index ε expressed by: ɛ = ∑ k ( y k - ∑ i a k - i × h i ) 2 ; is evaluated to adjust said recording condition, where 15≦m≦n.
16. The recording/reproducing apparatus according to claim 14 or 15 , wherein said optical recording medium is a phase-change optical recording medium, and wherein, upon forming said record mark group on said phase-change optical recording medium by irradiating said phase-change optical recording medium with the laser light, an overwrite operation is conducted twice or more before obtaining said reproduced waveform.
17. The recording/reproducing apparatus according to claim 13 , wherein a function of obtaining said reproduced signal includes the function of averaging three or more reproduced waveforms obtained by reproducing a plurality of record mark groups recorded by a plurality of recording pulses having the same waveform, or the function of averaging thee or more reproduced waveforms obtained by reproducing for a plurality of times a mark group recorded by a specified recording pulse waveform.
18. The recording/reproducing apparatus according to claim 15 , wherein said control section controls said recording condition by defining the following formula: R1 = ( n + 1 ) × ∑ i h i 2 ∑ i ( y k - ∑ i a k - 1 × h i ) 2 , and said control section further has a function of determining a recording or erasing laser power so as to satisfy 10×log R 1 >20-20(l/w) dB, given w being a beam diameter of the laser beam, given l being a shortest mark length among said record mark group.
19. The recording/reproducing apparatus according to claim 15 , wherein said control section controls said recording condition by defining the following formula: R2 = ( n + 1 ) × ∑ k y k 2 ∑ k ( y k - ∑ k a k - 1 × h i ) 2 , and said control section further has a function of determining a recording or erasing laser power so as to satisfy 10×log R 2 >21-20(l/w) dB, given w being a beam diameter of the laser beam, given l being a shortest mark length among said record mark group.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
February 5, 2003
October 9, 2007
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